Understanding Total Knee Replacement

A total knee replacement involves cutting away the damaged bone of the knee joint and replacing it with a prosthesis. This ‘new joint’ prevents the bones from rubbing together and provides a smooth knee joint.

If you are considering knee surgery the following total knee replacement information might help you understand the procedure and implants better.

Your knees work hard during your daily routine, and arthritis of the knee or a knee injury can make it hard for you to perform normal tasks. If your injury or arthritis is severe, you may begin experience pain when you�re sitting down or trying to sleep.

Sometimes a total knee replacement is the only option for reducing pain and restoring a normal activity level. If Taos Orthopaedic Institute and you decide a total knee replacement is right for you, the following information will give you an understanding about what to expect.

Implant Components
In the total knee replacement procedure, each prosthesis is made up of parts. The tibial component has two elements and replaces the top of the shin bone or tibia. This prosthesis is made up of a metal tray attached directly to the bone and a plastic spacer that provides the bearing surface.

The femoral component replaces the bottom of the thigh bone or femur. This component also replaces the groove where the patella, or kneecap, sits.

The patellar component replaces the surface of the knee cap, which rubs against the femur. Patellar component problems are a most common cause of knee replacement complications. For most patients, Taos Orthopaedic Institute uses a specially designed implant which eliminates the need for kneecap resurfacing. This state-of-the-art technique eliminates this most common cause of mechanical failure of total knee replacement!

The Procedure
Before you are taken to the operating room you�ll be given medication to help you relax, and the anesthetist will talk with you about the medications he�ll be using. You may have an injection which will make your leg numb for many hours after the surgery and take away pain. In the operating room, you will be placed under full anesthesia.

Once you are ‘under’, the surgeon will begin by making an incision in your leg to allow access to the knee joint. He’ll then expose the joint and place cutting jigs or templates on the end of the femur or thigh bone and the tibia or leg bone. These jigs allow the surgeon to cut the bone precisely so that the prosthesis fits exactly.

Now it’s time to place the prosthesis. This begins with the tibial prosthesis, which is cemented in place using special bone cement. Next the metal component is cemented to the femur. The plastic spacer is then attached to the tibial tray. This will provide the weight-bearing surface of the leg. If this component should wear out while the rest of the artificial knee is sound, it can be replaced. This is known as a revision. Finally, our state-of-the-art prosthesis and technique allow the patella to be spared while painful knee cap spurs are removed. The incision is closed, a drain is put in, and the post-operative bandaging is applied.

Returning Home
You will be discharged after three to five nights in the hospital when you can get out of bed on your own and walk with a walker or crutches.

At home you should begin ambulation with a support as tolerated. Keep your incision clean and dry and watch closely for any signs of infection.

You’ll continue your home exercise program and have home or outpatient physical therapy, where you will work on an advanced strengthening program and such exercises as stationary cycling, walking, and aquatic therapy.

Your long-term rehabilitation goals are a range of motion from 0 to at least 90 degrees of knee flexion, mild or no pain with walking or other functional activities, and independence in all activities of daily living.

Understanding Knee Replacement Alternative Bearing Material for Younger, Heavier or More Active Patients

OXINIUM is “Strong As An Ox!”
Not all implant devices are made of the same material. Due to significant advancements in technology, metallurgy and process, there is a revolutionary new material for implant devices that, quite literally, is “As Strong As An Ox!”

To date, cobalt chrome has been the material of choice for joint implants because of its strength and relative hardness. However, studies have shown that cobalt chrome implants roughen over time when implanted in your body. Every time a roughened replacement joint rubs against the plastic bearing surface, the plastic surface begins to wear out.

Laboratory studies have demonstrated that even a single scratch on the cobalt chrome surface can increase the rate of plastic wear by 10 times. Over time, the plastic surface wears out, and additional surgery is necessary to replace the worn implants. Recent studies have proven through controlled wear testing that a “scratched” or “roughened” cobalt chrome implant will dramatically increase the production of plastic wear debris, and substantially reduce the life span of an implant.

Oxinium or oxidized zirconium is the name of the material, and it is 4,900 times superior in terms of hardness, smoothness and resistance to scratching and abrasion compared to the cobalt chrome metal usually used for total knee replacement. Oxinium actually incorporates the best features of all available material options (ceramic and cobalt chrome) without the risks associated with either.

A younger, heavier or more active patient can expect an Oxinium replacement to be long-lasting and allow normal activities with less fear of undergoing a repeat replacement surgery.